Zinc Requirement of Hybrid Rice - Bhendi and its influence on Zinc Fractions in an Alfisol of Hyderabad, Andhra Pradesh

Field experiment was conducted for two consecutive years on students' farm, Hyderabad on a zinc-deficient Alfisol to assess the direct and residual effect of different rates and frequency of applied Zn on yield of hybrid rice and bhendi (okra), and distribution of Zn in different fractions, and depletion of fractions of Zn under hybrid rice-bhendi cropping system. Direct crop of hybrid rice responded to applied Zn up to 50 kg ZnSO₄ ha⁻¹ which could even meet the requirement of second residual crop included in the system. Application of Zn at highest dose i.e. 100 kg ZnSO₄ ha¹ had residual effects up to fourth crop i.e. bhendi in the system. Apart from the application of 50 kg ZnSO₄ ha⁻¹ to rice, if an additional dose of 25 kg ZnSO₄ ha⁻¹ is applied to the third crop of rice, significant response of bhendi (4^th crop) was observed. Depletion of water soluble plus exchangeable and complexed forms of Zn occurred to an extent of 45.0 and 8.7% at 0–15 cm and 41.5 and 5.92% at 15–30 cm depth. Build-up of organic, occluded and residual forms of Zn occurred. DTPA- extractable Zn was reduced to an extent of 5.08% after direct crop and to an extent of 18.6% after the fourth crop in the hybrid rice-bhendi cropping system.